This invention relates to an improved mandrel and mandrel assembly for growing graft tubes of living tissue and to a method for making the mandrel.
In the related applications identified above, which are hereby incorporated by reference, a mandrel assembly having a pair of cloth tubes on a flexible silicone rubber mandrel is implanted in a living body to grow a graft tube in the place where it is to be used or to grow a transplantable graft tube which may be autogenous, homologous, or heterologous. Such graft tubes may be used as arteries, veins, esophagus, ureters, bile ducts, or trachea.
The mandrel assembly disclosed in said related applications has been used successfully for a considerable period of time by skilled surgeons. When the mandrel assembly is implanted in a living body, connective tissue from the body grows through the double layers of the cloth to thoroughly encapsulate the cloth and fill both an inner space between the inner cloth layer and the mandrel and an intermediate concentric annular space between the two layers of cloth.
The inner layer of cloth serves primarily as a spacer element to hold the outer layer of cloth away from the mandrel, and the filling of the inner and intermediate spaces just mentioned assists in this purpose. Thus, the outer layer of cloth provides a primary reinforcement to strengthen the graft tube adjacent its outer surface where reinforcement is most effective. The inner cloth tube also provides additional or secondary reinforcement, the two layers of cloth thereby greatly strengthening the wall of natural body tissue.
When the graft is grown in situ, or the place where it is to be used, the graft tube is completely vascularized and is a living part of the body when the ingrowth of tissue is complete and the mandrel withdrawn, leaving a lumen in the tube. The ends of the graft tube are then anastomosed to the tube or tubes of the body which the graft tube is to serve.
When the graft tube is to be transplanted to another location in the same body, or to a different body, it is similarly completely vascularized during its period of growth but upon transplant it must establish a new blood supply system and when the new blood supply is established, the graft becomes a living part of the body in which it is implanted.
The objects of the present invention are to provide an improved mandrel and mandrel assembly for growing a graft tube, to provide a mandrel and mandrel assembly which do not require as much skill on the the part of the surgeon, to provide a mandrel and mandrel assembly which will more consistently grow graft tubes of uniform quality, to provide a more compliant mandrel, and to provide a method for making a compliant mandrel.